Smallpox was a systemic disease, officially eradicated since 1979 (WHO), caused by infection with the Variola major virus, whose only reservoir was infected humans.
HIV is a virus which attacks the immune system and causes a lifelong severe illness with a long incubation period. The end-stage of the infection, acquired immunodeficiency syndrome (AIDS), results from the destruction of the immune system.
Botulism is a serious paralytic illness caused by a nerve toxin produced by the bacterium Clostridium botulinum. The disease may occur after eating foods containing the toxin or due to development of the spores within the intestine of young children or within wounds.